| 摘要 |
<p>This invention pertains to a siloxane resin composition comprising R<1>SiO3/2 siloxane units, R<2>SiO3/2 siloxane units and (R<3>O)bSiO(4-b)/2 siloxane units wherein R<1 >is an alkyl group having 1 to 5 carbons, hydrogen, or mixtures thereof; R<2 >is a monovalent organic group having 6 to 30 carbons; R<3 >is a branched alkyl group having 3 to 30 carbons, b is from 1 to 3; and the siloxane resin contains from 2.5 to 85 mole percent R<1>SiO3/2 units, 2.5 to 50 mole percent R<2>SiO3/2 units and 5 to 95 mole percent (R<3>O)bSiO(4-b)/2 units. The siloxane resin is useful to make insoluble porous resin and insoluble porous coatings. Heating a substrate coated with the siloxane resin at a sufficient temperature effects removal of the R<2 >and R<3>O groups to form an insoluble insoluble porous coating having a porosity of 1 to 60 volume percent and a dielectric constant in the range of 1.5 to 3.0.</p> |
